Dark-eyed Junco

A regular breeding resident species, migrant, and regular in winter.  Dark-eyed Junco was an uncommon breeding species during the Minnesota Breeding Bird Atlas.

There are five subspecies of juncos, all with distinct characteristics that provide considerable misery for taxonomists. The subspecies that occurs in Minnesota, Junco h. hyemalis, breeds throughout the midwestern and northeastern United States and Canada west to Alaska. It integrates with J. h. carolinensis in the Appalachian Mountains from southern New York State to West Virginia (Figure 1). The highest densities of the Minnesota subspecies are found in the western United States and Canada (Figure 1).

Assigned a Continental Concern Score of 8/20 by Partners in Flight.

A permanent resident to short-distance migrant, the Dark-eyed Junco overwinters throughout the United States and parts of southern Canada south to northern Mexico.

Seeds, arthropods, waste grain, and some fruit primarily foraged from the ground.

Cup-nest in highly variable locations, but usually on or near the ground in roots, moss, or grasses.

Roberts (1932) emphasized a distribution in the northern coniferous forests. He described its southern extent from central Pine County northwest to Itasca Park and eastern Marshall County. He further stated the species was “found evenly distributed, nesting alike among the rocks and fallen needles under the pines on the upland and in the sphagnum moss beneath the Labrador tea of the spruce and cedar swamps of the lowlands.” He confirmed nesting in Aitkin, Marshall, Pine, and St. Louis Counties plus in Itasca Park. All confirmations were of nests with eggs or young, except in Pine County, which was labeled as “feeding young.”

Years later, Green and Janssen (1975) also labeled the junco’s distribution primarily in the northeastern and north-central regions but scarce among the western and southern margins of these regions. They included additional confirmed nesting in Carlton, Cook, and Lake Counties, plus an observation of two young birds in northern Chisago County in 1950. Several years later, Janssen (1987) suggested a more restricted breeding distribution south to northern Carlton and Crow Wing Counties. He also noted an extensive summer record in Otter Tail County in 1977 from June 2 to July 12. Along with Hertzel and Janssen (1998), he included confirmed nesting from 6 counties since 1970: Aitkin, Beltrami, Cook, Koochiching, Lake, and Lake of the Woods.

The Minnesota Biological Survey included 100 breeding observation locations and reinforced the junco’s primary distribution as northeastern Minnesota but also included potential breeding locations in northern Pine, northern Cass, eastern Marshall, and northern Roseau Counties (Minnesota Department of Natural Resources 2016).

The MNBBA included 241 records and all were confined to the northern portions of the Laurentian Mixed Forest Ecological Province, especially the northern tier of counties from eastern Roseau and Beltrami Counties to Cook County (Figure 2). Twelve confirmed nesting records were reported, with the only new county record from northeastern Itasca County (Figures 2 and 3; Table 1). Possible nesting was reported in Carlton, Cass, and Crow Wing Counties, at the southern extent of its breeding distribution in the state. Breeding observations were only reported in 3.3% (156/4,733) of the atlas blocks surveyed.

The MNBBA probability map identifies a very patchy distribution of the Dark-eyed Junco throughout northern and north-central Minnesota (Figure 4). Concentrations were predicted in the lowland coniferous forests in the Agassiz Lowlands Ecological Subsection of northern Beltrami, western Koochiching, and parts of Lake of the Woods Counties. In addition, pockets of moderate populations were predicted in northeastern Aitkin, and many areas of Lake and St. Louis Counties. Overall, the junco is not predicted to be found anywhere in Minnesota in high densities.

Roberts (1932) provided little evidence of breeding distribution changes in Minnesota; though he documented Dark-eyed Juncos feeding their young in Pine County. In addition, the record of young birds in northern Chisago County in 1950 suggested some nesting in that region of the state (Green and Janssen 1975). The MNBBA recorded no detections in the western counties of Clearwater or Marshall, places where the species had previously been detected. Certainly the difficulty in identifying the species by song may play a role in the lack of detections in this region, especially in distinguishing it from the more common Chipping Sparrow. However, the species’ white outer tail retrices are conspicuous, so observers are unlikely to have misidentified it if it had been present.

Cutright et al. (2006) reported breeding observations from southern Wisconsin in the early 1900s, and Brewer et al. (1991) reported possible breeding as far south as latitude 44^o north in the central portion of the lower peninsula of Michigan, which is the same latitude as southeastern Minnesota. In their review of the species in North America, Nolan et al. (2002) provided little evidence of historical changes in the Dark-eyed Junco’s breeding distribution in North America, but Cadman et al. (1987) emphasized its decline from southern Ontario, where it nested in the late 1800s.

In Minnesota, its historical record remains unclear. Southern and western portions of Minnesota were primarily prairie-grasslands and deciduous forests, unsuitable habitat for the species. The extent of these habitats was more limited in the southern regions of Wisconsin, Michigan, and Ontario. The limited information provided by Roberts (1932) suggests the species may have nested in more southerly (Pine County) and western locations (Marshall County) than it does today, especially where conifer forests existed, but its breeding distribution is unlikely to have been substantially more extensive in Minnesota.

*Note that the definition of confirmed nesting of a species is different for Breeding Bird Atlas projects, including the definition used by the Minnesota Breeding Bird Atlas, compared with a more restrictive definition used by the Minnesota Ornithologists’ Union. For details see the Data Methods Section.

Across North America, this species breeds in a wide variety of habitats, from boreal forest, pine and aspen forests, parklands, shrubby open areas, and even urban settings (Nolan et al. 2002). In Minnesota, however, it is largely associated with both upland (e.g., spruce-fir and pine forests) and especially lowland coniferous forests dominated by black spruce or tamarack (Figure 5; Niemi and Hanowski 1992a, b; Green 1995). Many sources report it in recently logged areas, but it is not often found in many of these habitats (Niemi and Hanowski 1984; Probst et al. 1992; Schulte and Niemi 1998), with the exception of the Agassiz Lowlands Ecological Subsection (Bednar et al. 2016). In the Agassiz Lowlands Ecological Subsection, Bednar et al. observed the species most often in black spruce-tamarack cover types but also in recently harvested lowland conifers.

Zlonis et al. (2017) recently reviewed the published literature for this species and identified positive associations with black spruce, evergreen forests, and stagnant lowland conifers as preferred habitat. In more detailed habitat models based on 40 breeding detections in the Agassiz Lowland Ecological Subsection, where the species was predicted to be relatively common (Figure 4), they identified black spruce forests within 200 m as the most significant variable in predicting its presence. The MNBBA also identified important habitats where the species was found during point counts. Bogs, upland and lowland coniferous forests, and pine forests were most associated with the species (Figure 6).

The National Forest Bird (NFB) Monitoring Program (Niemi et al. 2016) did not record the species very often during its June counts, likely because the Dark-eyed Junco vocalizes earlier in the season and before most breeding bird counts are initiated. It was identified most often in jack pine and lowland black spruce-tamarack forests.

The Partners in Flight program (Rosenberg et al. 2016) estimated the North American breeding population as 190 million adults. Canada alone estimated an adult population of more than 50 million birds (Environment Canada 2014). The MNBBA estimated a Minnesota breeding population of 107,000 breeding adults (95% confidence interval of 61,000 – 316,000), while the Partners in Flight Science Committee (2013) had previously estimated a much lower Minnesota breeding population of 34,000 breeding adults. Regardless, Minnesota does not constitute a large proportion of the global population of Dark-eyed Juncos.

The federal Breeding Bird Survey (BBS) trend for Minnesota has too few observations to be reliable, but the trend for the Boreal Hardwood Transition Region indicated a significantly declining trend of 2.09% per year from 1966 to 2015 (Figure 7). Declines were also significant but slightly less dramatic for the same period for all routes survey-wide (−1.38% per year), for all routes in the United States (−1.22% per year), and for all routes in Canada (−1.46% per year). PIF (Rosenberg et al. 2016) estimated an overall decline of 42% of the population from 1970–2014 in North America. In addition, Christmas Bird Counts survey-wide indicated a decline of 1.3% per year from 1959 to 1988 (Sauer et al. 1996), a trend very similar to the BBS results. The species was not common enough in the NFB counts to confidently identify a trend in the Chippewa or Superior National Forests.

Overall mean density estimates in the Chippewa and Superior National Forests were 0.08 and 0.11 pairs per 40 ha, respectively. Based on 18 routes in Minnesota from 1967 to 2015, the BBS also recorded an average of less than 1 detection per route. These estimates indicate that the species is rare to uncommon during breeding bird counts in June within these forests. However, the highest densities were reported from mature black spruce-tamarack bogs in the Agassiz Lowland Subsection, with an estimated 0.8 pairs per 40 ha.

The Continental Conservation score of 8/20 for the Dark-eyed Junco is relatively low. Therefore, this species is presently of limited conservation concern because of its wide breeding distribution and large overall population in North America. Its recent decline due to unknown causes, however, is of moderate concern (Environment Canada 2014). Nolan et al. (2002) identified nest predation as common, ranging annually from 20% to 80% in the Commonwealth of Virginia. Longcore et al. (2013) listed the Dark-eyed Junco as one of the top ten species killed at communication towers in the Prairie Potholes and Badlands regions in the midwestern United States. In its analysis of predicted changes due to climate in North America, Langham et al. (2015) and the National Audubon Society (2015) did not list the Dark-eyed Junco as a species of concern due to its large population and the potential availability of habitat further north in Canada and Alaska.